Hope is a good thing to have, because there is always a small chance that they may come back. I don't know anything about time travel, besides we both did it. I haven't traveled about in time here specifically, but I do know it's done. My own son has come back as an adult once. And the island did enjoy tossing about the Sully children quite a bit.
But that said... And I hate myself for having to say this, the chance is very small. This place enjoys it's cruelty. I would hate to see your hopes fly so very high, only to be dashed. Please be careful.
You're a good man and you deserve far better than this.